Handle relative and case insensitive file paths

UnityPy/environment.py

@@ -107,6 +107,16 @@ def load_file(
                 file = b"".join(file)
             else:
                 name = file
+                if not os.path.exists(file):
+                    # relative paths are in the asset directory, not the cwd
+                    if not os.path.isabs(file):
+                        file = os.path.join(self.path, file)
+                    # Unity paths are case insensitive, so we need to find "Resources/Foo.asset" when the record says "resources/foo.asset"
+                    if not os.path.exists(file):
+                        file = ImportHelper.find_sensitive_path(self.path, file)
+                    # nonexistent files might be packaging errors or references to Unity's global Library/
+                    if file is None:
+                        return
                 file = self.fs.open(file, "rb")
 
         typ, reader = ImportHelper.check_file_type(file)
@@ -155,7 +165,7 @@ def save(self, pack="none", out_path="output"):
         for fname, fitem in self.files.items():
             if getattr(fitem, "is_changed", False):
                 with open(
-                    self.fs.sep.join([out_path, ntpath.basename(f)]), "wb"
+                    self.fs.sep.join([out_path, ntpath.basename(fname)]), "wb"
                 ) as out:
                     out.write(fitem.save(packer=pack))
 

UnityPy/helpers/ImportHelper.py

@@ -1,4 +1,5 @@
-import os
+from __future__ import annotations
+import os
 from typing import Union, List
 from .CompressionHelper import BROTLI_MAGIC, GZIP_MAGIC
 from ..enums import FileType
@@ -127,7 +128,7 @@ def parse_file(
     name: str,
     typ: FileType = None,
     is_dependency=False,
-):
+) -> Union[files.File, EndianBinaryReader]:
     if typ is None:
         typ, _ = check_file_type(reader)
     if typ == FileType.AssetsFile and not name.endswith(
@@ -141,3 +142,20 @@ def parse_file(
     else:
         f = reader
     return f
+
+
+def find_sensitive_path(dir: str, insensitive_path: str) -> Union[str, None]:
+    parts = os.path.split(insensitive_path.strip(os.path.sep))
+
+    senstive_path = dir
+    for part in parts:
+        part_lower = part.lower()
+        part = next(
+            (name for name in os.listdir(senstive_path) if name.lower() == part_lower),
+            None,
+        )
+        if next is None:
+            return None
+        senstive_path = os.path.join(senstive_path, part)
+
+    return senstive_path